64Cu production via the 68Zn(p,nα)64Cu nuclear reaction: An untapped, cost-effective and high energy production route.

INTRODUCTION: Copper-64 (64Cu, t1/2 = 12.7 h) is a positron emitter well suited for theranostic applications with beta-emitting 67Cu for targeted molecular imaging and radionuclide therapy. The present work aims to evaluate the radionuclidic purity and radiochemistry of 64Cu produced via the 68Zn(p,nα)64Cu nuclear reaction. Macrocyclic chelators DOTA, NOTA, TETA, and prostate-specific membrane antigen ligand PSMA I&T were radiolabeled with purified 64Cu and tested for in vitro stability. [64Cu]Cu-PSMA I&T was used to demonstrate in vivo PET imaging using 64Cu synthesized via the 68Zn(p,nα)64Cu production route and its suitability as a theranostic imaging partner alongside 67Cu therapy. METHODS: 64Cu was produced on a 24 MeV TR-24 cyclotron at a beam energy of 23.5 MeV and currents up to 70 µA using 200 mg 68Zn encapsulated within an aluminum­indium-graphite sealed solid target assembly. 64Cu semi-automated purification was performed using a NEPTIS Mosaic-LC synthesis unit employing CU, TBP, and TK201 (TrisKem) resins. Radionuclidic purity was measured by HPGe gamma spectroscopy, while ICP-OES assessed elemental purity. Radiolabeling was performed with NOTA at room temperature and DOTA, TETA, and PSMA I&T at 95 °C. 64Cu incorporation was studied by radio-TLC. 64Cu in vitro stability of [64Cu]Cu-NOTA, [64Cu]Cu-DOTA, [64Cu]Cu-TETA, and [64Cu]Cu-PSMA I&T was assessed at 37 °C from 0 to 72 h in human blood serum. Preclinical PET imaging was performed at 1, 24, and 48 h post-injection with [64Cu]Cu-PSMA I&T in LNCaP tumor-bearing mice and compared with [68Ga]Ga-PSMA I&T. RESULTS: Maximum purified activity of 4.9 GBq [64Cu]CuCl2 was obtained in 5 mL of pH 2-3 solution, with 2.9 GBq 64Cu concentrated in 0.5 mL. HPGe gamma spectroscopy of purified 64Cu detected <0.3 % co-produced 67Cu at EOB with no other radionuclidic impurities. ICP-OES elemental analysis determined <1 ppm Al, Zn, In, Fe, and Cu in the [64Cu]CuCl2 product. NOTA, DOTA, TETA, and PSMA I&T were radiolabeled with 64Cu, resulting in maximum molar activities of 164 ± 6 GBq/µmol, 155 ± 31 GBq/µmol, 266 ± 34 GBq/µmol, and 117 ± 2 GBq/µmol, respectively. PET imaging in PSMA-expressing LNCaP xenografts resulted in high tumor uptake (SUVmean = 1.65 ± 0.1) using [64Cu]Cu-PSMA I&T, while [68Ga]Ga-PSMA I&T yielded an SUVmean of 0.76 ± 0.14 after 60 min post-injection. CONCLUSIONS: 64Cu was purified in a small volume amenable for radiolabeling, with yields suitable for preclinical and clinical application. The 64Cu production and purification process and the favourable PET imaging properties confirm the 68Zn(p,nα)64Cu nuclear reaction as a viable 64Cu production route for facilities with access to a higher energy proton cyclotron, compared to using expensive 64Ni target material and the 64Ni(p,n)64Cu nuclear reaction. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE: Our 64Cu production technique provides an alternative production route with the potential to improve 64Cu availability for preclinical and clinical studies alongside 67Cu therapy.

Free space optical link for biomedical applications.

Free space optics is an interesting alternative for telemetry with medical implants, due to the high data bandwidths available at optical frequencies. Especially implanted brain-computer interfaces gives rise to large data sets that needs to be transmitted transcutaneous. In this paper we show that it is possible to establish such a link at near-IR wavelengths using a modulated reflector in the implant, thus keeping the laser and the detector on the outside. In addition, we show that it will not only work on short, i.e. touch, distances but also at larger distances, in the range of a meter. We have used an electro absorption modulator to modulate the reflection of an external laser source back towards an external detector. The only part of this system that needs to be implanted is the modulator and drive electronics. The study has been done both by Monte-Carlo simulations of a multi-layer model of a rat skull, and with an experiment demonstrating the feasibility of the link when transmitted through biological tissue. The results show that it is possible to establish a transcutaneous link with an external laser source and light detector, and an internal modulated reflector.

Techniques for time-efficient isolation of human skin dendritic cell subsets and assessment of their antigen uptake capacity.

Dendritic cells (DCs) residing in skin are important sentinels for foreign antigens. Methods to facilitate studies of subsets of skin DCs are important to increase the understanding of various pathogens, allergens, topical treatments or vaccine components targeting the skin. In this study, we developed a new DC purification method using a skin graft mesher, clinically used for expansion of skin grafts, to accelerate processing of skin into nets that allowed efficient enzymatic disruption and single cell isolation. The reduction in processing time using the skin graft mesher enabled processing of larger skin samples and also limited the ex vivo handling of the specimens which is associated with maturation of DCs. In addition, a skin explant model to functionally monitor early events of antigen uptake by DC subsets in situ was developed. DCs isolated from epidermis represented a uniform CD1a(+) HLA-DR(+) CD11c(+) Langerin(+) DC-SIGN(-) DC-LAMP(int) DEC-205(int) Langerhans cell (LC) population whereas three subtypes of HLA-DR(+) CD11c(+) DCs were isolated from dermis based on their varying expression of CD1a. Epidermal LCs showed a significantly higher antigen uptake capacity of fluorescently-labelled ovalbumin (OVA) and dextran as compared to any of the dermal DC (dDC) subsets. In contrast, injection of antigen directly into skin explants followed by in situ imaging revealed that the majority of DCs with internalized antigen were localized in the dermis, likely as a consequence of the anatomical site for antigen delivery. These methods offer potency for various applications addressing antigen uptake, microbial DC interactions or other antigenic stimulation targeting the skin and can enhance our knowledge of basic DC biology in human skin.

Evolution of four gene families with patchy phylogenetic distributions: influx of genes into protist genomes.

BACKGROUND: Lateral gene transfer (LGT) in eukaryotes from non-organellar sources is a controversial subject in need of further study. Here we present gene distribution and phylogenetic analyses of the genes encoding the hybrid-cluster protein, A-type flavoprotein, glucosamine-6-phosphate isomerase, and alcohol dehydrogenase E. These four genes have a limited distribution among sequenced prokaryotic and eukaryotic genomes and were previously implicated in gene transfer events affecting eukaryotes. If our previous contention that these genes were introduced by LGT independently into the diplomonad and Entamoeba lineages were true, we expect that the number of putative transfers and the phylogenetic signal supporting LGT should be stable or increase, rather than decrease, when novel eukaryotic and prokaryotic homologs are added to the analyses. RESULTS: The addition of homologs from phagotrophic protists, including several Entamoeba species, the pelobiont Mastigamoeba balamuthi, and the parabasalid Trichomonas vaginalis, and a large quantity of sequences from genome projects resulted in an apparent increase in the number of putative transfer events affecting all three domains of life. Some of the eukaryotic transfers affect a wide range of protists, such as three divergent lineages of Amoebozoa, represented by Entamoeba, Mastigamoeba, and Dictyostelium, while other transfers only affect a limited diversity, for example only the Entamoeba lineage. These observations are consistent with a model where these genes have been introduced into protist genomes independently from various sources over a long evolutionary time. CONCLUSION: Phylogenetic analyses of the updated datasets using more sophisticated phylogenetic methods, in combination with the gene distribution analyses, strengthened, rather than weakened, the support for LGT as an important mechanism affecting the evolution of these gene families. Thus, gene transfer seems to be an on-going evolutionary mechanism by which genes are spread between unrelated lineages of all three domains of life, further indicating the importance of LGT from non-organellar sources into eukaryotic genomes.